All the projects will make use of the microinjection facility to introduce macromolecules (primarily RNA and DNA) into cultured mammalian cells. This centralized facility will provide equipment, supplies, and personnel for the whole program. This is a very cost effective way for all of the investigators to have access to techniques requiring skilled personnel and specialized equipment. The major equipment needed for microinjection is available in Dr. J. Smith's laboratory and will be used in this core. Major items available include a Nikon Diaphot inverted phase-contrast microscope, DeFonbrune micromanipulator, a Brown-Flaming micropipette puller, and video camera and monitor.